Add the Rust crate map to the servo library and dependency on libuv
auto merge of #1530 : larsbergstrom/servo/android_fixups, r=metajack

These two fixes are required for Android. We need to generate a toplevel crate map because it is used by both debugging and the libuv stuff. We also need to manually link against rustuv because we cannot dynamically inject it on Android.

r? @metajack